Novel three-controller average current mode control of DC-DC PWMconverters with improved robustness and dynamic response

摘要

This paper presents a novel average current mode control (ACC)nstrategy for the control of pulse width modulated (PWM) DC-DCnconverters, which represents a drastic improvement over conventionalnACC. This new method consists of the addition of an auxiliary controllerninto the control loop, besides the current and voltage regulators. Thenmodel-based auxiliary controller can increase the closed loopnsmall-signal bandwidth of Buck derived converters, preserving loop gainncrossover frequency and stability margins over significant changes ofnthe power stage passive elements values, the load and the line voltage.nMoreover, this control scheme shows much better disturbance rejectionnproperties, i.e., closed loop impedance and audiosusceptibility, thannconventional ACC. From a control theory point of view, robustnperformance is achieved preserving stability. A Buck prototype has beennexperimentally tested with different LC output filters, line and loadnconditions, including discontinuous conduction mode. Measurements of thensmall signal frequency response of the converter have been carried out,nshowing the improvement achieved by the proposed control scheme. Thenempirical large signal response of the converter under load steps isnalso shown in order to validate the concept